1. Field of the Invention
The present invention relates to a ladder program creation apparatus. Specifically, the present invention relates to a ladder program creation apparatus that sets a custom ladder command included in a ladder program.
Priority is claimed on Japanese Patent Application No. 2012-004235, filed Jan. 12, 2012, the content of which is incorporated herein by reference.
2. Description of the Related Art
All patents, patent applications, patent publications, scientific articles, and the like, which will hereinafter be cited or identified in the present application, will hereby be incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains.
One type of control apparatus is an indicating controller that has a sequence control function in a ladder language widely used for PLCs (programmable logic controller), as described in “New Product Introduction: UT Advanced Series Digital Indicating Controllers”, Yokogawa Technical Report, Yokogawa Electric Corporation, Mar. 8, 2010, Vol. 53, No. 1 (2010), p. 56.
By utilizing a sequence control function, it has been possible to implement, within a controller, not only the functionality of a controller, but also the functionality of compact PLCs, timers, and switches or the like that have been conventionally used as peripheral devices.
By doing this, it is possible to reduce the conventionally required peripheral devices and interconnections, thereby enabling a reduction of the overall cost.
By using a simple configuration and a familiar ladder language, it is possible to expect a reduction in the labor required for program development.
Additionally, because data within the controller can be used in a ladder program, utilization in various applications can be envisioned, such as input compensation, and the combining of PID control and sequence control.
FIG. 7 is a block diagram illustrating an example of a configuration of a ladder program creation apparatus in which a ladder program is created in a controller in accordance with the related art. The ladder program creation apparatus includes an indicating controller 1, a personal computer 2, and a parameter setting tool program 3 installed in the personal computer 2. In FIG. 7, the personal computer 2 is connected to an indicating controller 1. The parameter setting tool program 3 is provided by the manufacturer of the controller, and is installed in the personal computer 2.
The indicating controller 1 is used by an engineer implementing a sequence control system, who operates the personal computer 2 in which the parameter setting tool program 3 is installed so as to create/input/set a desired ladder program such as shown in FIG. 8 corresponding to the sequence control system that is to be implemented.
FIG. 8 is a view illustrating an example of a display screen of the personal computer 2 when creating a ladder program based on the parameter setting tool program 3 in accordance with the related art. As shown in FIG. 8, a ladder program creation display screen 21 is shown on the display screen of the personal computer 2. The ladder program creation display screen 21 includes a command display area 2a and a program editing area 2b. In the command display area 2a, a plurality of basic commands (for example, 13 types) and application commands (for example, 67 types) based on the parameter setting tool program 3 are displayed. In the example of FIG. 8, the basic commands are 13 types of LD.AND, LDN.ANDN, OR, ORN, OUT, SET, E_SET, RST, E_RST, TIM, CNT, DIFU, and DIFD. The application commands include comparison commands such as GT, LT, GE, LE, EQ, and NEQ and arithmetic operation commands such as ADD, E_ADD, and the like.
The engineer creating the ladder program selects desired commands from a plurality of basic commands and application commands displayed on the command display area 2a. The engineer creates/inputs/sets a desired ladder program by placing the selected commands at prescribed positions in the program editing area 2b. 
FIG. 9 is a view representing each of the lines L1 to L7 of the ladder program displayed in the ladder program creation display screen 21 in the form of equations when the ladder program of FIG. 8 is created in accordance with the related art. As shown in FIG. 9, in the program editing area 2b included in the ladder program creation display screen 22, each of the lines L1 to L7 of the ladder program is represented in the form of equations. In the example of FIG. 9, each of the lines L1 to L7 of the ladder program is represented in the form of equations as follows.1st Line L1: DAT01+DAT02=DAT10→DAT01+DAT022nd Line L2: DAT03+DAT04=DAT11→DAT03+DAT043rd Line L3: DAT10÷DAT11=DAT10→(DAT01+DAT02)/(DAT03+DAT04)4th Line L4: DAT05+DAT06=DAT11→DAT05+DAT065th Line L5: DAT07+DAT08=DAT12→DAT07+DAT086th Line L6: DAT11÷DAT12=DAT11→(DAT05+DAT06)/(DAT07+DAT08)7th Line L7: DAT10×DAT12=DAT11→{(DAT01+DAT02)/(DAT03+DAT04)}×{(DAT05+DAT06)/(DAT07+DAT08)}
The parameter setting tool program 3 installed in the personal computer 2 is a program developed for the purpose of implementing as a software ladder program a circuit implemented on a relay board. Thereby, the parameter setting tool program 3 is capable with regard to coding expressions of input/output processing, and is not good at coding expressions of arithmetic calculation processing.
That is, when coding arithmetic calculation processing in a ladder program based on the parameter setting tool program 3, the coded program becomes complex, as shown in FIG. 8. Thereby, it is difficult from the coded program to read the original equations shown in FIG. 9 on which it is based.